Current Medicinal Chemistry - Volume 24, Issue 5, 2017

This mini-review article provides an overview on the use of magnetic materials for the analysis of protein biomarkers. In particular, the advantage provided by magnetic solid phase extraction will be discussed with selected examples, considering untargeted analysis for screening new biomarker proteins and targeted investigation on known and suggested new biomarkers. Aspects, such as enrichment efficiency over conventional techniques, ease of use, functionalization versatility and automation will be considered, together with quantification and deeper structure elucidation provided by coupling selective or specific enrichment to powerful characterization techniques, such as mass spectrometry.

Magnetically-assisted delivery of therapeutic agents to the site of interest, which is referred to as magnetic drug targeting, has proven to be a promising strategy in a number of studies. One of the key advantages over other targeting strategies is the possibility to control remotely the distribution and accumulation of the nanocarriers after parenteral administration. However, preparation of effective and robust magnetically responsive nanocarriers based on superparamagnetic iron oxide nanocrystals (SPIONs) still represents a great scientific challenge, since spatial guidance of individual SPIONs is ineffective despite the presence of high magnetic field gradient. A strategy to overcome this issue is the clustering of SPIONs to achieve sufficient magnetic responsiveness. In this mini-review, we address current and future strategies for the design and fabrication of magnetically responsive nanocarriers based on SPIONs for magnetically-targeted drug delivery, including the underlying physical requirements, the possibility of drug loading, and the control of drug release at the targeted site.

Cubosomes are self-assembled nanostructures that often form on dispersion of polar lipids in aqueous environments. The nanoparticles are analogous to liposomes but contain a complex internal self-assembled structure providing a point of difference to relatively simple liposomes. They exhibit a range of attractive properties such as having a high surface area, being able to incorporate both hydrophobic and hydrophilic molecules and controlled release. Consequently cubosomes are of increasing interest in fields such as drug delivery, and diagnostic imaging, in particular as a carrier for magnetic resonance imaging contrast agents. Over the last decade the incorporation of various contrast agents into the cubic mesophases has demonstrated improved relaxivity and resolution, as well as addressing other limitations of commercially available agents by increasing circulation time, stability and targeting. This minireview provides a brief overview of what cubosomes are, how they can be made, how they are characterised and also summarise the findings from the studies that have used cubosomes to develop better contrast agents for MRI, as well as highlight some potential for future developments.

Nanoparticles are finding many applications in medicine and other fields like photonics. Magnetic nanoparticles have additional advantages in medicine over non-magnetic hard nanoparticles, as their magnetic properties make them ideal for hyperthermic applications in therapy and for sensitive diagnostic imaging applications. I review the literature on computational models of the magnetic properties of nanoparticles specifically. Such models have the potential to accelerate the design of magnetic nanoparticles for medical applications. Much of the current literature relates to the modelling of magnetic nanoparticles for inducing hyperthermia in aberrant cells, with significant bodies of work aimed at simulating and predicting properties for medical imaging and targeted delivery of drugs and gene therapies.

Bimetallic particles based on gold and iron have been gathering increasing interest in biomedical applications because of the synergic combination of the plasmonic features of the inert gold component with the magnetic properties of the iron or iron oxide fraction, that makes these hybrid nanomaterials suitable for imaging, therapeutic and analytical applications. In this minireview, we emphasize gold-based nanomaterials with potential for Magnetic Resonance Imaging, focusing on Au-Fe hybrid systems as potential T2-weighted, goldbased contrast agents.

Cellulose is a natural linear biopolymer, which is constituted of an assembly of cellulose nanofibrils in a hierarchical order. Nanocelluloses in particular show great promise as a cost-effective advanced material for biomedical applications because of their biocompatibility, biodegradability, and low cytotoxicity. Moreover, with their chemical functionality they can be easily modified to yield useful products. While nature uses the hierarchical nanostructure of cellulose as the load-bearing constituent in plants, a significant amount of research has been directed toward the fabrication of advanced cellulosic materials with various nanostructures and functional properties. Such nanocelluloses are widely applied in medical implants, tissue engineering, drug delivery, wound healing, diagnostics, and other medical applications with real examples in this field. There are also emerging fields being developed to use nanocelluloses and their composites in more novel ways in biomedical applications such as 3D printing and magnetically responsive materials. In this mini-review, recent advances in the design and fabrication of nanocellulose-based materials and composites are presented with a special emphasis on their suitability for material requirements for biomedical applications as well as the new directions and challenges that the materials might face in the future.

The utilization of graphene-based nanomaterials combined with magnetic nanoparticles offers key benefits in the modern biomedicine. In this minireview, we focus on the most recent advances in hybrids of magnetic graphene derivatives for biomedical applications. We initially analyze the several methodologies employed for the preparation of graphene-based composites with magnetic nanoparticles, more specifically the kind of linkage between the two components. In the last section, we focus on the biomedical applications where these magnetic-graphene hybrids are essential and pay special attention on how the addition of graphene improves the resulting devices in magnetic resonance imaging, controlled drug delivery, magnetic photothermal therapy and cellular separation and isolation. Finally, we highlight the use of these magnetic hybrids as multifunctional material that will lead to a next generation of theranostics.

Neural stimulation provides a means for scientists to investigate brain functions and neurological diseases. There is also mounting interest in using remote stimulation of neuronal circuits for brain-machine interfaces. In this review, we highlight recently developed technologies utilizing magnetic nanoparticles to generate heat or exert mechanical forces for remote control of brain circuits and compare these with conventional (electrical stimulation and drugs) and second-generation (ultrasound and light) techniques. We also present some of the challenges and progress in areas like genetics, nanoparticle synthesis and energy delivery devices to translate the use of these innovative nanoparticle-based platforms in research and clinical settings.